ABAP_to_the_Future

Automating the Test Process 3.4
while you are going to be using a program to dynamically determine what objects
need to be created, that same program might as well also dynamically determine
what type (subclass) those created objects should be.
Listing 3.22 is an example of this approach; this code attempts to achieve the
same thing as you saw in the SETUP method in Listing 3.15, but with fewer CREATE
OBJECT statements. If you look at the definition of the SETUP method earlier in the
chapter, you’ll see three CREATE OBJECT statements, and in each case the object
you’re creating has to be defined by a DATA statement. (Some objects also need
data parameters that are elementary, my dear Watson.)
Listing 3.22 rewrites the same SETUP method, using a Z class created to use dependency
injection. Look at this like a newspaper: look at the four high level method
calls first (which represent the headlines), and then dive into the implementation
of each component method (representing the actual newspaper article) one at a
time.
First, set some values for elementary data parameters. Then, specify any subclasses
you want to substitute for real classes. Finally, create an instance of the
class under test.
DATA: mo_class_under_test TYPE REF TO ycl_monster_simulator.
zcl_bc_injector=>during_construction( :
for_parameter = 'ID_CREATOR' use_value = md_creator ),
for_parameter = 'ID_VALID_ON' use_value = sy-datum ).
"We want to use a test double for the database object
zcl_bc_injector=>instead_of(
using_main_class = 'YCL_MONSTER_PERS_LAYER'
use_sub_class = 'YCL_MOCK_MONSTER_PERS_LAYER' ).
zcl_bc_injector=>instead_of(
using_main_class = 'YCL_LOGGER’
use_sub_class = 'YCL_MOCK_LOGGER' ).
zcl_bc_injector=>create_via_injection(
CHANGING co_object = mo_class_under_test ).
Listing 3.22 SETUP Method Rewritten Using Z Statement
As you can see, when using this approach you do not have to have DATA statements
to declare the database access object or the logging object. In addition, you
only have one CREATE statement. This may not seem like much in this simple
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